Abstract : This report summarizes the most extensive set of upper-air data ever collected over Antarctic sea ice in winter, the data that we obtained using radiosondes during the U.S.-U.S.S.R. Weddell Polynya Expedition. The report includes a description of the two radiosonde systems that we used, a chronological listing of all 110 soundings that we made during the expedition, a discussion of measured and derived quantities, listings of all of the sounding data, and plots to 5 km of the potential temperature profile from each sounding. (Author)